MinDepth - LeetCode

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int minDepth(struct TreeNode* root) {
    if (root == 0)
        return 0;
    int leftDepth = minDepth(root->left);
    int rightDepth = minDepth(root->right);
    if (leftDepth == 0 && rightDepth == 0)
        return 1;
    else if (leftDepth == 0)
        return rightDepth+1;
    else if (rightDepth == 0)
        return leftDepth+1;
    else
        return (leftDepth < rightDepth ? leftDepth+1 : rightDepth+1);
}